Smolin video LQG online course

1. Jan 20, 2006

marcus

Last edited by a moderator: Apr 21, 2017
2. Jan 29, 2006

marcus

Last edited: Jan 29, 2006
3. Jan 29, 2006

marcus

Smolin says he will continue giving lectures in the course every Wednesay thru February, and then in March the day may change sometime to Thursday.

So far my favorites of what I have watched are Lectures #1 and #3.
I'm impressed with Smolin's ability as an explainer.

Last edited: Jan 29, 2006
4. Jan 29, 2006

duke_nemmerle

This is an excellent find, I will check it out soon

5. Feb 2, 2006

robousy

nice find...but waaaay too much topology for me.
want/need to learn this someday but its completely new to me and I've been doing physics for years.

6. Feb 2, 2006

marcus

Now as of today SIX lectures are available.

when there were just 4 then my favorites were #1 and #3

(they are the morning halves, parts #2 and #4 were given in afternoon, maybe the morning audience is better, or Smolin is fresher, or maybe it just worked out that way)

Actually I was surprized at how basic and understandable the geometry/topology stuff is.
when you quantize gravity you are quantizing the SHAPE OF SPACETIME, so naturally you need geometric/topological tools because the geometry of spacetime is not a fixed framework but a dynamic uncertain thing. You need a handle on all possible geometries so that you can have quantum states of geometry which are blurred, uncertain, fuzzy shapes of spacetime----geometry governed by probability instead of certainty.

And that is what spacetime really is. It is not some clear fixed thing AFAIK.

So nobody should be surprised if you encounter a few new math concepts. The remarkable thing is that they aren't all that bad---they seem quite natural, as Smolin presents them IMHO.

I'm going to try #5 now.

7. Feb 9, 2006

marcus

Parts 7 and 8 of the Smolin lectures on Quantum Gravity are now available online

8. Feb 11, 2006

marcus

We should have a study group to go over these lectures one by one and figure out what the main ideas of each one are.

these are good lectures IMO.

I think it would repay the effort of watching them and discussing them here at PF

9. Feb 11, 2006

Staff Emeritus
Has anyone had trouble watching them? I was watching the first one today and my IE browser crashed. I'll try again with Firefox.

But if I succeed, I'll be up for a study group. Perhaps we could start a subforum like they did in Philosophy for A Place for Consciousness?

Update: Same thing with Firefox. "Firefox has encountered a problem and needs to close". And at the same point in the video; just about 30 seconds - certainly less than a minute - into his discussion of the volume operator. He has chalked the words "operator on Hilbert space" on the board and begun to talk when it happens. Drat!

Last edited: Feb 11, 2006
10. Feb 11, 2006

marcus

thanks for trying!
the only way we can assess what is possible and what isn't
is if people are willing to try it.

I have no trouble. But my wife and son forced me to get DSL last year. I would never have treated myself to it, unprodded, and now I see the point.
the whole thing is effortless and ordinarily runs without a hitch.
I have watched most of the 8 lectures so far---with some interruptions.

I would say that your being unable to participate more or less rules out having a study group here at PF----that is my guess, but we will see what happens.

11. Feb 11, 2006

Staff Emeritus
I noticed something else, my virus checker got turned off. Now I ran a virus scan just yesterday and found nothing, but this is very supicious. I'll try a couple of things to see if I have some intrusive software that is screwing things up.

Also do you have the hep-th number for the Intro to GR as a Gauge Theory paper that he chalked on the board? I couldn't interpret his handwriting even though I have now seen it twice.

12. Feb 11, 2006

marcus

The paper he referred to for Intro to GR as a Gauge Theory
is http://arxiv.org/abs/hep-th/0209079

He said the relevant sections (for Lecture 1) were sections 2 and 3

I just looked at beginning of Lecture 1 video so I am sure about that.

At some point, according to Christine, he refers to one by Wipf
http://arxiv.org/abs/hep-th/9312078
but probably that is not in Lecture 1---some other in the series.

he says he will use Baez and Muniain. I don't have that book, regret to say.

Last edited: Feb 11, 2006
13. Feb 12, 2006

Staff Emeritus
Thank you very much Marcus. I had written it down as "...029" insted of "...079", which is why I couldn't find it.

I don't either. It's out of print.

AND it's a http://dogbert.abebooks.com/servlet/SearchResults?an=Baez+and+Muniain&y=9&x=37" [Broken]:surprised

Last edited by a moderator: May 2, 2017
14. Feb 12, 2006

George Jones

Staff Emeritus
Wow!!!

Thinking that this result might be an anomaly, I also did a seach, with this http://www.bookfinder.com/search/?ac=sl&st=sl&qi=JlDfOJFh7JdFyFXvP.EEiMm0ZF0_9485734881_2:12:18".

I bought the book new shortly after it came out - I forget what I paid. Much of the book is a standard modern intro to differential geometry, so this material is easily found in other books. I'm (k)not sure what it does with knots though - I don't have it at hand.

Most university libraries probably have the book.

The idea for a study group is great, but, unfortunately, I won't be able to participate as much as I would like. I learn new things quite slowly, and I am swamped with work right now.

I will (at least) lurk, though.

Regards,
George

Last edited by a moderator: May 2, 2017
15. Feb 14, 2006

Ratzinger

I heard a second edition of that book is in preparation. I wish Baez would add the lecture notes on quantum gravity from his website to it. Then I could imagine it would nicely complement Penrose last book.

(And finally all the motivated but lesser-smart laymen like myself could make more sense of this cool stuff called mathematical physics.)

And please start a study group.

16. Feb 15, 2006

marcus

Lectures #9 and #10 are now available! I will start listening in a moment.

George Jones, glad to hear that you are interested and will watch----the important thing is to catch the lectures themselves whether or not you contribute comments here. But it would be nice if you did help out. It is actually a lot of work just to watch each lecture and say what it is about in one or two sentences! We need that kind of summary outline list for all 10 (so far) lectures.

I expect we will have a study group if two things
A. selfAdjoint turns out to be able to get the lectures with his internet connection. If we do it, we should all be able to participate---or a fair chunk of us anyway, not just a small splinter.

B. someone starts posting a list of the topics of each lecture, little by little. I think that would clearly be helpful (I cant remember what the general outline is) and I think it is all it takes to get started.

BTW Christine Dantas has posted a list of the SYSTEM REQUIREMENTS for watching the Smolin Lectures.

Last edited: Feb 16, 2006
17. Feb 16, 2006

Staff Emeritus
My browser only gives me a few minutes of viewing time before crashing, but by stepping through the video from one crash point to the next I have now succeeded in viewing the whole first video. Needless to say this is tedious and I am not going to try the second one till tomorrow! Nevertheless I did take notes and am ready to discuss on the first.

18. Feb 16, 2006

CD

If you can disable the video plugin and manage to click through the slides on your own I can put up a passworded copy of videos. I don't really know what their usage rules are but since I use linux I started stripping and saving the videos.

Also, a study group would be great.

19. Feb 17, 2006

Staff Emeritus
I don't quite know how to do this. I wouldn't want the slides apart from the videos. But let me see how session two goes and we'll talk. At this point I am up for a study session.

Did you see that Christine Dantas had some questions about the poset structure of the moves and how they related to Causal Sets and to GR causality? Of course causality in GR does force a poset structure on events. Two events have a causal relation if they are timelike related, in each other's light cones. But causality isn't even defined for spacelike related events; different coordinates will have them in different orders.

Smolin is saying that his moves satisfy the axioms for causal sets. I don't recall exactly what they are. Can anybody copy them to this thread?

20. Feb 17, 2006

CD

Well I have the first 5 available to download. Just pm me if anyone needs them and I'll send you an address and password. You'd just have to click through the slides manually instead of letting the javascript or whatever it is that is doing it automatically while watching the videos.

Causal set C

Transitivity
$$\forall{x,y,z}\epsilon{C}(x\prec{y}\prec{z}\Rightarrow{x}\prec{z} )$$
Irreflexivity
$$\forall{x}\epsilon{C}(x!\prec{x})$$
Locally Finite
$$\forall{x,z}\epsilon{C}(cardinality ( y \epsilon C | x \prec y \prec z ) < \infty)$$

Last edited: Feb 17, 2006